纤维质燃料水平填充床反向阴燃传播特性研究

基于两步反应动力学机理(包括燃料热解和燃料的氧化),建立了二维非稳态燃料填充床阴燃的数学模型.该模型既考虑了固相和气相之间的热传递,也考虑到了气体在多孔介质内扩散系数的变化.辐射换热采用扩散近似方式予以表达.数值模拟结果表明:阴燃传播速度随着来流速度的增大而增大,但当来流速度超过0.35 cm/s时,阴燃速度增长幅度大大减小;来流速度对阴燃最高温度影响不大.同时还模拟了燃料阴燃过程中气体组分(O2、CO、CO2及H2O)和固体成分(燃料、焦炭)的变化以及温度分布情况.图8,表2,参12.     

3D C/C复合材料的电弧驻点烧蚀及机理分析

采用电弧驻点烧蚀试验方法,测试细编穿刺毡增强体C／C复合材料的烧蚀率,并采用电子扫描显微镜观察烧蚀表面形貌。研究结果表明:在电弧驻点烧蚀试验条件下,3D C／C复合材料具有较好的烧蚀性能;C／C复合材料的烧蚀过程主要受热化学烧蚀和机械剥蚀2种烧蚀机制的共同作用,二者相互促进,以机械剥蚀为主;微观烧蚀形貌主要由热化学化蚀导致,宏观烧蚀形貌则主要是机械剥蚀所致。     

固溶处理对7A55铝合金断裂韧性的影响

采用金相组织观察、拉伸实验、Kahn撕裂试验、扫描电镜、透射电镜等方法研究固溶处理对7A55铝合金断裂韧性的影响。研究结果表明:固溶温度对7A55铝合金断裂韧性影响显著,7A55铝合金在450～490℃时固溶,随着温度上升,可溶性粒子减少,断裂韧性增加,到480℃时断裂韧性达到最大值;当温度超过480℃时,由于晶粒的长大,断裂韧性又开始下降;7A55铝合金有很大的淬火敏感性,当以慢速淬火时,晶界非共格析出物尺寸粗大,对断裂韧性不利。     

ZnCo2O4尖晶石纳米粉体的新型共沉淀法合成及表征

以草酸为沉淀剂、乙醇为溶剂,通过新型共沉淀法合成分子前躯体锌钴草酸复合盐ZnCo2(C2O4)3.4H2O,对该前躯体在不同温度下热处理即可制得锌钴尖晶石粉体.利用热重分析仪(TGA)和差示扫描量热仪(DSC)对前躯体热分解过程分别进行热失重分析和动力学分析.结果表明,前躯体热分解仅经历2个热失重过程(脱结晶水和最后分解)且最后分解过程遵循随机成核和核随后生长单一的动力学机理,活化能不随转化率的变化而变化.由此说明前驱体为草酸复合盐而不是二元混合盐.利用X-射线衍射(XRD)、红外光谱(IR)和透射电子显微镜(TEM)等分析手段对尖晶石粉体进行表征.结果显示,前躯体在低温段450~650℃煅烧2 h即可获得单相、颗粒细小均匀的尖晶石粉体,高温750℃煅烧,得到ZnO和缺锌的锌钴尖晶石的混合物.     

Experimental study on CO2/CO of typical lining materials in full-scale fire test

Lining materials are widely used in buildings to cover walls and ceilings. Combustible linings may produce a potential high fire hazard in buildings. Once ignited, it propagates fire and accelerates the enclosure fire growth. Two types of lining materials were studied during the tests： block board and plywood. The test was conducted in an ISO 9705 room, where linings were mounted on walls without the ceiling. By changing the heat output of the burner, the ventilation, etc., the concentrations of CO2/CO of different lining materials were researched. The effect of test conditions on the production of CO2/CO of different lining materials was investigated, and useful experimental data were provided for the further development of numerical modeling to simulate enclosure fire growth lined with combustible materials.     

Coherent thermal radiation in thin films and its application in the emissivity design of multilayer films

The infrared transmission spectra of a 0.54-μm-thick Ge film and a 20-μm-thick Si film were experimentally measured. As the incident radiation was in the wavelength range from 1.5μm to 10μm, the Ge film demonstrated a strongly spectral coherence. However, thermal radiation of the Ge film was found to be spatially incoherent due to its extreme thinness. The Si film exhibited significantly spectral and spatial coherence. The results confirmed that thermal radiation of a monolayer film could be coherent spectrally and spatially if the film thickness was comparable with the wavelength. The optical characteristic matrix method was applied to calculate the transmission spectra of the Si and Ge film, and the results agreed well with the measurements. This method was further used to analyze two multilayer films composed of five low emissive layers. Their emissivities were found to be highly emissive at a certain zenith angle, and the emissive peak could be controlled by careful selection of film thickness.     

试验检测是提高公路工程质量的关键

分析了加强公路工程试验检测工作的必要性和重要性,指出了提高公路工程质量试验检测的措施。     

纳米四水羟基硝酸氧铋的制备及在氮气气氛下的热分解动力学

利用反相微乳液法制备出了纳米四水羟基硝酸氧铋[Bi6O4(OH)4](NO3)6(H2O)4,并以热分析为手段对纳米[Bi6O4(OH)4](NO3)6(H 2O)4的热分解过程和非等温热分解动力学机理进行了研究.动力学研究确定了[Bi6O4(OH)4](NO3)6(H2O)4脱硝酸根反应属于球对称的三维扩散的D3机理,热分解表观活化能为E=98.90033 kJ/mol,lnA=27.13109.     

人工神经网络在审计领域的应用

介绍了人工神经网络的基本特征,对国内外将人工神经网络技术应用于审计的有代表性的研究成果进行了综述,建议我国也应开展此类研究,且应将研究重点放在审计实质性测试方面。     

梁格法在斜腿刚架桥结构分析中的应用

为对小跨径变截面斜腿刚架桥进行准确而简便的分析计算,采用梁格法并通过动静载试验与有限元计算结果进行验证,提出在建立梁格模型时应对计算跨径和斜腿刚域进行合理的模拟,所得结果满足精度要求.